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APPLIES TO: All API Management tiers
The http-data-source
resolver policy configures the HTTP request and optionally the HTTP response to resolve data for an object type and field in a GraphQL schema. The schema must be imported to API Management as a GraphQL API.
Note
Set the policy's elements and child elements in the order provided in the policy statement. Learn more about how to set or edit API Management policies.
<http-data-source>
<http-request>
<get-authorization-context>...get-authorization-context policy configuration...</get-authorization-context>
<set-backend-service>...set-backend-service policy configuration...</set-backend-service>
<set-method>...set-method policy configuration...</set-method>
<set-url>URL</set-url>
<include-fragment>...include-fragment policy configuration...</include-fragment>
<set-header>...set-header policy configuration...</set-header>
<set-body>...set-body policy configuration...</set-body>
<authentication-certificate>...authentication-certificate policy configuration...</authentication-certificate>
</http-request>
<backend>
<forward-request>...forward-request policy configuration...</forward-request>
<http-response>
<set-body>...set-body policy configuration...</set-body>
<xml-to-json>...xml-to-json policy configuration...</xml-to-json>
<find-and-replace>...find-and-replace policy configuration...</find-and-replace>
<publish-event>...publish-event policy configuration...</publish-event>
<include-fragment>...include-fragment policy configuration...</include-fragment>
</http-response>
</http-data-source>
Name | Description | Required |
---|---|---|
http-request | Specifies a URL and child policies to configure the resolver's HTTP request. | Yes |
backend | Optionally forwards the resolver's HTTP request to a backend service, if specified. | No |
http-response | Optionally specifies child policies to configure the resolver's HTTP response. If not specified, the response is returned as a raw string. | No |
Note
Except where noted, each child element may be specified at most once. Specify elements in the order listed.
Element | Description | Required |
---|---|---|
get-authorization-context | Gets an authorization context for the resolver's HTTP request. | No |
set-backend-service | Redirects the resolver's HTTP request to the specified backend. | No |
include-fragment | Inserts a policy fragment in the policy definition. If there are multiple fragments, then add additional include-fragment elements. |
No |
set-method | Sets the method of the resolver's HTTP request. | Yes |
set-url | Sets the URL of the resolver's HTTP request. | Yes |
set-header | Sets a header in the resolver's HTTP request. If there are multiple headers, then add additional header elements. |
No |
set-body | Sets the body in the resolver's HTTP request. | No |
authentication-certificate | Authenticates using a client certificate in the resolver's HTTP request. | No |
Element | Description | Required |
---|---|---|
forward-request | Forwards the resolver's HTTP request to a configured backend service. | No |
Note
Except where noted, each child element may be specified at most once. Specify elements in the order listed.
Name | Description | Required |
---|---|---|
set-body | Sets the body in the resolver's HTTP response. | No |
xml-to-json | Transforms the resolver's HTTP response from XML to JSON. | No |
find-and-replace | Finds a substring in the resolver's HTTP response and replaces it with a different substring. | No |
publish-event | Publishes an event to one or more subscriptions specified in the GraphQL API schema. | No |
include-fragment | Inserts a policy fragment in the policy definition. If there are multiple fragments, then add additional include-fragment elements. |
No |
The following example resolves a query by making an HTTP GET
call to a backend data source.
type Query {
users: [User]
}
type User {
id: String!
name: String!
}
<http-data-source>
<http-request>
<set-method>GET</set-method>
<set-url>https://data.contoso.com/get/users</set-url>
</http-request>
</http-data-source>
The following example uses a liquid template, supported for use in the set-body policy, to return a list in the HTTP response to a query. It also renames the username
field in the response from the REST API to name
in the GraphQL response.
type Query {
users: [User]
}
type User {
id: String!
name: String!
}
<http-data-source>
<http-request>
<set-method>GET</set-method>
<set-url>https://data.contoso.com/users</set-url>
</http-request>
<http-response>
<set-body template="liquid">
[
{% JSONArrayFor elem in body %}
{
"name": "{{elem.username}}"
}
{% endJSONArrayFor %}
]
</set-body>
</http-response>
</http-data-source>
The following example resolves a mutation that inserts data by making a POST
request to an HTTP data source. The policy expression in the set-body
policy of the HTTP request modifies a name
argument that is passed in the GraphQL query as its body. The body that is sent will look like the following JSON:
{
"name": "the-provided-name"
}
type Query {
users: [User]
}
type Mutation {
makeUser(name: String!): User
}
type User {
id: String!
name: String!
}
<http-data-source>
<http-request>
<set-method>POST</set-method>
<set-url>https://data.contoso.com/user/create </set-url>
<set-header name="Content-Type" exists-action="override">
<value>application/json</value>
</set-header>
<set-body>@{
var args = context.GraphQL.Arguments;
JObject jsonObject = new JObject();
jsonObject.Add("name", args["name"])
return jsonObject.ToString();
}</set-body>
</http-request>
</http-data-source>
The following example resolves the orderById
query by making an HTTP GET
call to a backend data source and returns a JSON object that includes the customer ID and type. The customer type is a union of RegisteredCustomer
and GuestCustomer
types.
type Query {
orderById(orderId: Int): Order
}
type Order {
customerId: Int!
orderId: Int!
customer: Customer
}
enum AccountType {
Registered
Guest
}
union Customer = RegisteredCustomer | GuestCustomer
type RegisteredCustomer {
accountType: AccountType!
customerId: Int!
customerGuid: String!
firstName: String!
lastName: String!
isActive: Boolean!
}
type GuestCustomer {
accountType: AccountType!
firstName: String!
lastName: String!
}
For this example, we mock the customer results from an external source, and hard code the fetched results in the set-body
policy. The __typename
field is used to determine the type of the customer.
<http-data-source>
<http-request>
<set-method>GET</set-method>
<set-url>https://data.contoso.com/orders/</set-url>
</http-request>
<http-response>
<set-body>{"customerId": 12345, "accountType": "Registered", "__typename": "RegisteredCustomer" }
</set-body>
</http-response>
</http-data-source>
For more information about working with policies, see:
Events
Mar 17, 9 PM - Mar 21, 10 AM
Join the meetup series to build scalable AI solutions based on real-world use cases with fellow developers and experts.
Register now